The small handheld computer or personal digital assistant (PDA) has become a popular tool in the business world and more recently in personal communications. These devices have incorporated wireless functions, cellular phone functions, personal audio, camera and video functions so that the market for such devices have expanded well beyond the business person to the individual. The modern PDA operates as a multifunction device that many individuals carry with them at all times.
The PDA performs as a technology platform for the development of many new value-added portable devices that can be integrated as hardware or software add-ons to the PDA or linked through wireless functions. There is an ever growing market for PDA add-ons as the penetration of users continues to expand from business applications to personal applications.
A relevant class of PDA add-on devices has been developed to improve the means of getting information into and out of the device. Cameras based PDA add-ons are particularly effective because a large volume of data, typically 1 Megabyte to 10 Megabytes, can be collected optically and electronically in a sub-second period of time. Closely related to optical imaging is the field of optical scanning of documents. With the addition of an optical scanner to a PDA, especially a PDA that has wireless or cellular capabilities, one can perform such tasks as, for example, portable faxing of documents from the field, or, the scanning and uploading of a serial number from the field so that useful product information could be rapidly and accurately downloaded to a technician during a repair process.
With respect to the prior art, there are examples of optical scanning devices that could be used in conjunction with a PDA. One example is an optical wand. Optical wands are currently commercially available and may communicate with PDAs via an external cable, but these are not seamlessly integrated and require an extra hand-held device. For example, Faulkerson, U.S. Pat. No. 4,804,949 discloses a scanning device in combination with a computer mouse connected via an umbilical cord to an external computer for OCR processing and text display. Faulkerson does not teach the on-board integration of optical scanning functions directly into a PDA.
Liao, U.S. Patent application No. 2004/0093444 A1 shows a PDA converted into an optical scanning device by adding an optical scanner assembly onto the back surface. Liao also discloses the application of scanning business card data into a PDA as bit-mapped images. Liao does not include a mechanism for illuminating the object to be scanned nor does he provide for simultaneous viewing of the object during the scan nor does he provide a mechanism for real-time image conversion to digital characters.
A similar disclosure is read in Huang, U.S. Patent Application No. 2002/0169509 A1 in which the author discloses a handheld device, such as a PDA, capable of optical scanning. Huang discusses a feeder scanner design in which the PDA is situated inside a base housing and the documents are fed through a scanner channel via a set of rollers. Huang's design limits the scanned document sizes to those that can fit through the housing and otherwise suffers from similar limitations as Liao.
In Tsai, U.S. Patent Application No. 2003/0151780, a scanning device is disclosed which includes a chassis for housing a PDA. Tsai also discloses an optical sensing assembly engaged with the transmission assembly so as to transfer the speed signal of the movement of the scanning device. Tsai's invention, while not limited by the document size, suffers from some of the same general limitations as the other designs, namely that the viewing of the document is limited to a bit-mapped image of the scanned input and that there is no immediate conversion to a standard digital character format. Real-time scanning of text directly into standard byte or word character format would realize a significant improvement in portability over the prior art, since text files composed of standard digital characters have much smaller file sizes compared to image file formats.